Applicants claim, under 35 U.S.C. xc2xa7 119, the benefit of priority of the filing date of Dec. 20, 2001 of a German patent application, copy attached, Serial Number 101 62 735.1, filed on the aforementioned date, the entire contents of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method for determining the signal running time between a position measuring system and a processing unit which are connected with each other via a digital interface, wherein data words of defined length are transmitted between the position measuring system and the processing unit via the digital interface, and ascertaining of the signal running time between the position measuring system and the processing unit takes place. The present invention furthermore relates to a device for executing the method.
2. Discussion of Related Art
In the context of a data transmission between several position measuring systems and a downstream-arranged processing unit via a digital interface, certain problems result in particular in the case of long transmission paths. Therefore, not inconsiderable running times on the respective data line result in this case. The resultant delay times must be taken into account for the correct further processing of the various data by the processing unit. If now there are configurations of several position measuring systems which are connected with a common, downstream-connected processing unit, the task arises, prior to the actual measuring operation, to determine the respective signal running times as exactly as possible, so that they can be suitably taken into consideration afterwards.
It is therefore an object of the present invention to disclose a method for as precise as possible a determination of the signal running time between a position measuring system and a processing unit which communicate with each other via a digital interface.
This object is attained by a method for determining a signal running time between a position measuring system and a processing unit, which are connected with each other. The method includes transmitting data words of defined length between a position measuring system and a processing unit and transmitting a first data word from the processing unit to the position measuring system. Transmitting a first incoming running time measuring signal from the processing unit to the position measuring system during the transmitting the first data word and determining a first position signal regarding a relative chronological position of said the running time measuring signal in relation to the first data word. Following an end of transmission of the first data word, transmitting the first running time measuring signal and the first position signal as binary data words to the position measuring system. Transmitting a second data word from the position measuring system to the processing unit and determining a second position signal regarding a chronological relative position of the first running time measuring signal with respect to said the data word. Following an end of transmission of the second data word, transmitting the second running time measuring signal and the second position signal as binary data words to the processing unit. Ascertaining a length of time between the transmitting of the first running time measuring signal and receipt of the second running time measuring signal by the processing unit and determining a signal running time for transmission of data between the position measuring system and the processing unit from the ascertained length of time.
The present object is furthermore attained by a device for determining a signal running time between a position measuring system and a processing unit, which are connected with each other. The device includes a first position signal generator that generates a first position signal regarding a relative chronological position of a first running time measuring signal with respect to a first data word, which are both transmitted from a processing unit to a position measuring system. A first transmitter that transmits the first running time measuring signal and the first position signal, each as a binary data word, to the position measuring system at the end of transmission of the first data word to the position measuring system. A second position signal generator that generates a second position signal regarding a relative chronological position of the first running time measuring signal with respect to a second data word, which is transmitted from the position measuring system to the processing unit to a position measuring system. A second transmitter that transmits a second running time measuring signal and the second position signal, each as a binary data word, to the processing unit after the end of transmission of the second data word. A timer that ascertains a length of time between transmission of the first running time measuring signal and reception of the second running time measuring signal by the processing unit and a signal running time generator that determines a signal running time from the length of time.
In accordance with the present invention, a principle as already described in German Patent Application 100 30 357.9, to whose disclosure specific reference is being made here, is employed in a changed form for the precise determination of the signal running time.
Analogous to the process in the mentioned document it is now possible in accordance with the present invention to transmit running time measuring signals with high chronological precision between the position measuring system and the processing unit. The end result is an exact determination of the signal running times between the position measuring system and the processing unit.
The signal running time determined in this way is subsequently suitably used or taken into consideration in the course of further processing of the transmitted data.
Further advantages as well as details of the present invention ensue from the following description of an exemplary embodiment by the attached drawings.